Methods and apparatus for substantially reducing nonlinear distortion using multiple nonlinear ...

43 Pages·2013·2.75 MB·English

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US 20040222851A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2004/0222851 A1
Weldon (43) Pub. Date: NOV. 11, 2004
(54) METHODS AND APPARATUS FOR Publication Classi?cation
SUBSTANTIALLY REDUCING NONLINEAR
DISTORTION USING MULTIPLE (51) Int. Cl.7 ..................................................... .. H03F 1/26
NONLINEAR DEVICES (52) US. Cl. .......................................... .. 330/151; 330/149
(76) Inventor: glglgmas Paul Weldon, Charlotte, NC (57) ABSTRACT
Correspondence Address: Methods and apparatus are provided for substantially reduc
ALSTON & BIRD LLP ing and/or canceling nonlinearities of any order in circuits,
BANK OF AMERICA PLAZA devices, and systems such as ampli?ers and mixers. In
101 SOUTH TRYON STREET’ SUITE 4000 particular, methods and apparatus are provided for substan
CHARLOTTE NC 282804000 (Us) tially reducing and/or canceling third order nonlinearities in
’ circuits, devices, and systems such as ampli?ers and mixers.
(21) APPL No. 10/794,000 A ?rst coupler is used to split an input signal into tWo
equal-amplitude in-phase components, each component is
(22) Filed; Man 5, 2004 processed by tWo nonlinear devices With different nonlin
earities, and a ?nal combiner, such as a 180-degree hybrid,
Related US, Application Data recombines the processed signals 180 degrees out of phase
and substantially reduces and/or cancels the undesired non
(62) Division of application No. 10/101,005, ?led on Mar. linear distortion components arising due to nonlinearities in
19, 2002, noW Pat. No. 6,794,938. the nonlinear devices.
354
364 \ 368 350
\ Ampli?er I
352 360
Input \ _' \ - . Output
. Coupling . Coupling >
1 Means Means I
362 372
356
\ 310
[ Ampli?er f
366
f 358 f f I
374 \ 376 378 380
Adaptive Control and Feedback
Means
Patent Application Publication Nov. 11, 2004 Sheet 1 0f 21 US 2004/0222851 A1
10
44
14 . 3° -
\ 18 ~ \ 35
%L ' Ampli?er 1 Delay I 50
42 ' 38
20 +
Input \ Output
i Y Attenuator z _ i
12 __ 40
24 32
1s 26 f
\ + \ p’ 34
Delay -— E Ampli?er _
22 28»
Fig. 1 (Prior Art)
Patent Application Publication Nov. 11, 2004 Sheet 2 0f 21 US 2004/0222851 A1
60
64
\ so
72 1 Amplifier f
62 68
75 78
Input 0 g 0 0 Output
3 180 § 0- 1801 ‘ 3
70 84
66
82
Ampli?er
Fig. 2 (Prior Art)
Patent Application Publication Nov. 11, 2004 Sheet 3 0f 21 US 2004/0222851 A1
100
.104
132 .116
' ' 112 \
‘ ’ Nonlinear
Z \ Device I 136
130 402
' ' _ r 1.08
\ _ _ V /122 124\ _ / _
In'p'ut % 0% 0 0 Output
3 0 180 $0 180 3
106 e
f “ \ ' 1118
Nonlinear
Device
134
Fig. 3
Patent Application Publication Nov. 11, 2004 Sheet 4 0f 21 US 2004/0222851 A1
140
144
\ 156
152
1 Ampli?er
142
Input \
Coupling
; Means
150
146
\ 158
f Ampli?er f
1 54'
Fig. 4
Patent Application Publication Nov. 11, 2004 Sheet 5 0f 21 US 2004/0222851 A1
500
S
Splitting an input signal at an input coupling means into
?rst and second in-phase coupled signals. The ratio of
the second coupled signal power, p;, to the ?rst coupled -‘ 5 1 0
signal power, p1, is K = l0log|o(p2/p|) dB, withpi andpz //\/
in milliwatts.
Processing the ?rst coupled signal at a ?rst nonlinear
device and the second coupled signal at a second
nonlinear device. The ?rst nonlinear device having a
gain, G1 dB and a third order output intercept point
OIP31dBrn. The second nonlinear device having a gain,
6; dB and a third order output intercept point OIP32
ddeBvimc eTs haen dre tlhaet icoonusphlipi nogf mtehea n?srs bt eainndg smeocsotn nde narolyn linear/W
>2(O[P31 - OIP32) = 3(G1 - G2 - K), where G is not
equal to G2 + K.
Subtracting the output signal of the second nonlinear
device from the output signal of the ?rst nonlinear
device to yield a ?nal output signal that substantially
reduces third order nonlinear distortion.
530
Fig. 5
Patent Application Publication Nov. 11, 2004 Sheet 6 0f 21 US 2004/0222851 A1
600
S
Splitting an input signal at an input coupling means
into ?rst and second in-phase coupled signals. The
ratio of the second coupled signal, x;, to the ?rst //'\_/ 0
coupled signal, an, being k = xzlxl.
(
Processing the ?rst coupled signal at a ?rst nonlinear
device and the second coupled signal at a second
nonlinear device. The ?rst nonlinear device has a
Taylor series expansion, y, = a0 + mx, + a2x|2 + 03x‘3 +
an? and the second nonlinear device has a Taylor
series expansion y; = be + bx; + bzxzz + bye; + bgc;4
. . ., with output denoted y.‘ and y;' and with input / /\/
denoted x1 and x2 respectively, such that the
relationship between the ?rst and second nonlinear
devices and the input coupling means is most nearly k
Subtrac?ng the output signal of the second nonlinear
device from the output signal of the ?rst nonlinear
device to yield a ?nal output signal that substantially
reduces nonlinear distortion of order n. 0
Fig. 6'
Patent Application Publication Nov. 11, 2004 Sheet 7 0f 21 US 2004/0222851 A1
170
172
Nonlinear
Load
Output
114 - 5
_ \ 176
Input
Nonlinear
i Device
178
Fig. 7
Patent Application Publication Nov. 11, 2004 Sheet 8 0f 21 US 2004/0222851 A1
180
1%
188 1
, /
184
M
Output
\
192
186
Input ‘ I /
1'90
Patent Application Publication Nov. 11, 2004 Sheet 9 0f 21 US 2004/0222851 A1
CC _ 200
208
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202
204
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206
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